#define _CRT_SECURE_NO_WARNINGS 1
#include<iostream>
using namespace std;
 struct ListNode {
      int val;
      ListNode *next;
      ListNode() : val(0), next(nullptr) {}
      ListNode(int x) : val(x), next(nullptr) {}
      ListNode(int x, ListNode *next) : val(x), next(next) {}
  };
 
class Solution {
public:
    ListNode* addTwoNumbers(ListNode* l1, ListNode* l2) {
        int t = 0;
        ListNode* cur1 = l1;
        ListNode* cur2 = l2;
        ListNode* newhead = new ListNode(0);
        ListNode* prev = newhead;
        while (cur1 || cur2 || t)
        {
            if (cur1)
            {
                t += cur1->val;
                cur1 = cur1->next;
            }
            if (cur2)
            {
                t += cur2->val;
                cur2 = cur2->next;
            }
            prev->next = new ListNode(t % 10);
            prev = prev->next;
            t /= 10;
        }

        ListNode* as = newhead->next;
        delete newhead;
        return as;
    }
};